For wireless communication, we need to increase the data throughput as applications are handling more and more data. Channel bonding (i.e. using more than one channel frequency at a time) is a known technique to extend the data rate of a wireless solution. More recently, the used of the spatial dimension, with MIMO techniques, has emerged: the capacity improvement reaches the same order than the channel extension, i.e. doubling the number of antennas at TX and RX sides also doubles the bit rate. MIMO related techniques enable to significantly increase the throughput and/or reliability of wireless transmissions while keeping constant the transmitted power and allocated spectrum bandwidth. This feature makes these techniques particularly attractive for wireless systems in many configurations (e.g. for point-to-point communication, or point-to-multipoint communication or for broadcasting systems).
In addition, recent wireless solutions (such as WiFi) may integrate a DFS (Dynamic Frequency Selection) mechanism, meaning an ability to dynamically move from one channel to another, all antennas moving simultaneously from one frequency to another. Indeed, a drawback of this technique is that is not adapted to various types of situations.